Two conductor dead end



'May 14 1963 F. P. BARlcEvlc Erm. 3,089,916

TWO CONDUCTOR DEAD END 2 Sheets-Sheet 1 Filed Feb. 15, 1961 May 14 1963 F. P. BARlcL-:vlc .E1-AL 3,089,916

Two CONDUCTOR DEAD END 2 Sheets-Sheet 2 Filed Feb. 15, 1961 Ali QN WN mwN NN afa/We 5 United States Patent O nois Filed Feb. 15, 1961, Ser. No. 89,463 7 Claims. (Cl. 174-79) .This invention relates to a dead end which is capable of deadending two conductors.

Dead end refers to a device by means of which the tension of the line conductor may be transmitted to a supporting structure. As such, it must embody line gripping means, and is generally used in combination with a tap for a drop Wire leading into the house, for example, the main characteristic of which is that the service wire or tap conductor does not take up any substantial stress.

The general rule is that a separate dead end is provided for each conductor, although there are exceptions as where a pair of insulated Wires can be engaged by a single gripping device.

An object of this invention is to provide a single dead-end device having two gripping devices and which is so arranged that two lines or conductors can be dead ended by the single device.

Our invention is particularly suitable for use with parallel insulated line wire, an example of which is the commercial product known as C rural wire. C rural line wire consists of two high strength copper clad steel wires which are jacketed in an extruded polyethylene insulation material, the conductors being spaced 1A from each other. The conductors are not twisted, and the jacket is generally severable so that two separate jacketed conductors can be brought out to make end connections.

lIn this type of wire, the jacket cannot be gripped because it exhibits poor adhesion with respect to the copper of the conductor; also it has very low tensile strength.`

rTherefore separate dead ends have been required, one for each conductor.

C rural line wire is normally used for telephone, but similar types are used in rural two wire power distribution.

It is another object of this invention to provide a deadend device of the type described which is so constructed and arranged as to minimize the current leakage which would ordinarily occur in a device of this type, particularly under adverse Weather conditions.

The foregoing objectives are attained first, by construction the two wire gripping devices and tensile members as the opposite legs of a single U-shaped dead-end structure which are electrically isolated from each other, and secondly, by offsetting the ends of the U-shaped structure so Vthat any current leakage along the surface of the jacket of the wire pair will occur along a comparatively long current leakage path.

Other` objects, features and advantages will become apparent as the description proceeds.

With reference now to the drawings in which like reference numerals designate like parts:

FIG. 1 is a side elevation of a preferred embodiment of our inventionr shown in association with the wire pair to which it is to be connected;

FIG. 2 is an elevation of the dead end as installed;

FIG. 3 is a fragmentary section taken along line 3-3 of FIG.

FIG. 4 is a section taken along line 4-4 of FIG. 5;

FIG. 5 is a section taken along line 5--5 of FIG. 4; and

FIG. 6 is a view of one of the hook means before closing.

With reference now to FIGS. 1 and 2, the reference numeral `'10 designates generally the dead end, and the reference numeral 11, a conductor pair. The latter comprises two conductors 12 and 13 encased in a common jacket 14, but which may severable so as to provide separate insulated conductors as shown in FIG. 1.

The dead end 10 comprises a generally U-shaped structure which may be connected to a support 15, such as a house or post, by means of an insulator spool 16 and a bracket 17, the spool 16 being held in the bracket by means of a suitable pin `18.

The dead end 10 comprises two tensile members or supporting wires 20 and 21 which are arranged end to end and secured to each other by a connecting member 22 which is formed of insulating material. The ends of the supporting wires 2l) and 21 may be connected to the stripped ends 2t)l of the conductors 12 and 13 by means of compression sleeves 23 and 24. In the embodiment shown, the compression sleeves may be preassembled with the dead end.

Suitable taps 26 and 27, in the form of split bolt connectors or the like, may also be -preassembled on the supporting wires 201 and 21 so that the usual flexible drop wires, not shown, may be electrically connected to the conductors 12 and 13.

The supporting wires 20 and 21 may have a greater or lesser degree of exibility so that the tension of the conductors 12 and 13 may be equally distributed between the supporting wires 20 and 21, due to the fact that one of the supporting wires is trained around the insulating spool 16. As such, the supporting wires may comprise flexible stranded wires, or a solid hard wire formed of stainless steel, or some other type of wire having ilexibility characteristics somewhere in between the stranded wire on the one hand and the hard wire on the other. v

In the embodiment shown, the support wires 20 and 21 are formed of a so-called hard wire which is commonly used in this trade due to its extremely high tensile strength. Hard wire of this type is generally considered rather stiff, but nevertheless it has sucient flexibility so that if there is a variation of say from 5 to 16% in the oisetting distance between the stripped ends 25 of the conductors 12 and 13, then preforming of the supporting wire 21 Iwill not appreciably interfere with the equalization of tension previously mentioned.

According to this embodiment, the U-shape of the dead-end structure 10 is provided 'by preforming the Supporting wire 21 into a U-shape as shown in FIGS. 1 and 2. Assuming that the supporting wires 20 and 21 are of substantially equal length, the arrangement shown results in an Oisetting of the compression sleeves 23 and 24 from each other by a substantial distance. In preparing the conductor pair 11 for installation, the ends of the separate conductors 12 and 13 are cut so that the conductor 13 extends beyond the end of conductor 12 by a distance suicient to match the offsetting of the compression sleeves, and any minor variation in cutting is automatically taken up by the flexibility of the hard wire support member 21.

The connecting member 22 is formed of a material having high internal electrical resistivity and high resistance to surface leakage. We have found a suitable material to be a glass ber reinforced polyester cast resin. The glass ber is of random orientation, and a silica dust filler may be used to decrease the cost without materially affecting the electrical properties.

The inner ends of the supporting wires 20 and 21 are suitably embedded in the material of the connecting memaosaele ber 22 as shown in FlGS. 4 and 5 We have found that an extremely strong mechanical connection may be effected by forming the inner ends of the supporting Wires 20 and 21 so as to provide hook means 28 and 29 which interlink with each other, but which nevertheless are separated from each other at all points by a distance which depends on the dielectric properties of the material from which the connecting member 22 is made. For instance, in the case of a iilled and reinforced polyester resin, a spacing of Ms inch is more than sufficient to withstand any electrical potential encountered in normal communication or low tension distribution work.

The advantage of providing interlinking hook means is that the tension transmitted from supporting Wire 20 to supporting -wire 21 is transmitted through the connecting member 22 in the form of a compressive stress of the material which separates the hook means at these points.

The hook means may be initially formed as open hooks as shown in FIG. 6 each of which have a bent end 30, so that each hook means can be closed upon itself and the bent end 30 snapped over the shank of the hook, as shown in FIGS. 3 and 4. In the case of some resins, of which the polyester resin above mentioned is an example there is comparatively low adhesion between the resin and the hard wire bail with the result that under extremely heavy tensile stresses, there is a tendency for the hard wire supporting member to snake out of the connecting member, if merely an open hook were to be provided. However, by closing the hook upon itself, and especially lby providing portions of small radius, such as the bent ends 30, this tendency is eliminated.

The supporting members 20 and 21, for reasons of manufacturing economy, can be formed identically, and the outer ends may be serrated as at 31 in FIG. 4, to improve the mechanical connection with the compression sleeve 23.

The parts of the dead end can be readily assembled with each other by providing a jig for maintaining the closed hooked ends 28 and 29 of the supporting members 20 and 21 in spad relationship with each other in a mold, and then pouring in the resin. Of course, other resins may be used equally effectively such as epoxy, or the connecting member 22 may be injection molded with a phenolic resin. The use of hard wire connecting members facilitates the maintenance of the spaced relationship of the parts during assembly or molding, and the same applies with wire stock having a much greater degree of llexibility. However, with certain types of stranded wire supported members which might be extremely flexible, a suitable dielectric spacing member may be used, and the support members maintained in the jig under tension during the assembly or molding operation, the free ends of the extremely flexible Wire being provided with heads, or being othelwise suitably anchored to prevent snaking.

The operation of the dead end has been described in detail in connection with the description of the various parts. To summarize the same, in the `installation of this dead end, the conductor pair 11 is first split down the middle between the conductors 12 and 13, and the one conductor is cut shorter than the other, and the ends are stripped. Then, the dead end is placed around the insulator spool 16, the stripped ends 20 of the conductors 12 and 13 inserted within the compression sleeves 23 and 24, and the latter compressed, and then the drop wires (not shown) are secured to the taps 26 and 27.

We have found that for use with C rural line wire an offsetting of approximately 111/2 inches provides a current leakage path along the surface of the jacket 14 which is suiiciently long as to eliminate any current leakage at electrical potentials which might be encountered under abnormal conditions. Similarly, if a connecting member 22 of polyester resin is approximately three inches long and one inch in diameter, the current leakage path along its surface is sufficiently long as to avoid any l current leakage under abnormal conditions. amples allow for the usual safety factor.

The hard wire used for the support members 20 and 21 is well adapted to withstand the vibration and Wear which is encountered over a period of many years. A suitable hard wire stock, for instance, is Type 304 stainless steel having a diameter of ysubstantially .109 inch. This hard wire stock is very strong, having an ultimate tensile strength of from 120,000 to 140,000 pounds per square inch.

The C-rural line wine referred to herein, may either be copper clad or galvanized.

The taps 26 and 27 may be of any suitable type, including the split bolt connectors shown, or a compression rtap of the same general type as that shown in Klein Patent No. 2,327,651, August 24, 1943.

Although only a preferred embodiment of our invention has been shown and described herein, it will be understood that various modifications and changes may be made in the construction shown without departing from the spirit of our invention as pointed out in the appended claims.

We claim:

1. A dead end for a wire pair in the form of a U-shaped structure comprising two tensile members arranged end to end, and a connecting member formed of insulating material, the adjacent end portions of said tensile members being embedded in said connecting member, and each adjacent end portion including hook means which interlinks the hook means of the other end porl tion, said hook means being separated from each other at all points by the material of said connecting member so as to provide electrical isolation of each tensile member with respect to the other, one of said tensile members being U-shaped, and the remote ends of said U-shaped structure being offset longitudinally one from the other to prov-ide offset terminals for connection `to the two conductors of said wire pair.

2. A dead end as claimed in claim 1 in which said tensile members are formed from stainless steel hard wire stock.

3. A dead end as claimed in claim 1 -in which said hook means are each closed upon themselves to provide a closed loop, the free end of each hook means being bent, and engaging the shank of the hook to maintain said hook means in closed position.

4. A two conductor dead end in the form of a U-shaped structure comprising t-wo tensile members arranged end to end, 'a connecting member formed of insulating material, the adjacent end portions of said tensile members being embedded in said connecting member, and each adjacent end portion including hook means ywhich interlinks the hook means of the other end portion, said hook means being separated from each other at all points .by the material of said connecting member so as to provide electrical isolation of each tensile member with respect to the other, one of said tensile members being U-shaped, and the remote ends of said Ushaped structure being offset longitudinally one from the other, and means located at said remote ends for making electrical connection to two conductors in tension transmitting relationship.

5. A dead end as claimed in claim 4 in which said connection means comprise compression sleeves.

6. A dead end as claimed in claim 4 having tap means mounted on each of said tensile members for making electrical connection to a pair of drop wires.

7. A dead end as claimed in claim 4 in which said insulating material is a polyester resin.

These ex# Martin May 20, 1919 Klein Jan. 27, 1959 

1. A DEAD END FOR A WIRE PAIR IN THE FORM OF A U-SHAPED STRUCTURE COMPRISING TWO TENSILE MEMBERS ARRANGED END TO END, AND A CONNECTING MEMBER FORMED OF INSULATING MATERIAL, THE ADJACENT END PORTIONS OF SAID TENSILE MEMBERS BEING EMBEDDED IN SAID CONNECTING MEMBER, AND EACH ADJACENT END PORTION INCLUDING HOOK MEANS WHICH INTERLINKS THE HOOK MEANS OF THE OTHER END PORTION, SAID HOOK MEANS BEING SEPARATED FROM EACH OTHER AT ALL POINTS BY THE MATERIAL OF SAID CONNECTING MEMBER SO AS TO PROVIDE ELECTRICAL ISOLATION OF EACH TENSILE MEMBER WITH RESPECT TO THE OTHER, ONE OF SAID TENSILE MEMBERS BEING U-SHAPED, AND THE REMOTE ENDS OF SAID U-SHAPED STRUCTURE BEING OFFSET LONGITUDINAL ONE FROM THE OTHER TO PROVIDE OFFSET TERMINALS FOR CONNECTION TO THE TWO CONDUCTORS OF SAID WIRE PAIR. 